I upgraded video card from a 5850 to a 6970. I get nothing but blue screen indicating a hardware problem. I tried to "fix" the problem numerous times but could not. I put the 5850 back in and everything is running smoothly. FYI, I did make sure the correct driver was installed for each card. I'm not sure why the 6970 would be causing my machine to blue screen. I have a Gigabyte P55A UD3 board and an 850W Corsair modular PSU.